Changestodetect – Rockwell Automation Logix5000 Controllers Controller Information and Status Programming Manual User Manual

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Chapter 4 Change detection

Attribute Name

Description

Access

ChangesToDetect

Used to specify which changes are monitored. When a monitored change
occurs, the Audit Value is updated.

GSV/SSV

ChangesToDetect

The ChangesToDetect mask is a 64-bit value. Each bit of the ChangesToDetect

mask corresponds to a particular event that could cause the Audit Value to change.

Important: Change detection is unavailable on the RSLogix Emulate 5000 Controller and the SoftLogix5860 Controller.

If a bit is set to a value of 1, the corresponding event is monitored for changes and

when a change for that event occurs the AuditValue updates. If a bit is set to a

value of 2, the corresponding event is not monitored and does not affect the Audit

Value. The default Audit Value of: 0xFFFFFFFFFFFFFFFF indicates that all

events are monitored.

Tip: The Audit Value updates when the controller is online.

Some events always update the audit value when they occur. For example, the

audit value changes when a project is downloaded to the controller, or when

ChangesToDetect is reconfigured. These types of events are not included in the

ChangesToDetect mask.

You can configure the ChangesToDetect mask programmatically using SSV, GSV

and MSG instructions.

Tip: You can use the Security tab in the Controller Properties dialog box to configure Change Detection if you are using

version 20 or later of the application. See

Use the Set System Value (SSV) instruction to write to the ChangesTo Detect

attribute and the Get System Value (GSV) instruction to read the ChangesTo

Detect attribute programmatically.

Rockwell Automation Publication 1756-PM015F-EN-P – October 2014